CN114361393A

CN114361393A - Method for simply preparing self-supporting silicon cathode and application of self-supporting silicon cathode in lithium/sodium battery

Info

Publication number: CN114361393A
Application number: CN202210017003.0A
Authority: CN
Inventors: 冯金奎; 安永灵; 田园
Original assignee: Shandong University
Current assignee: Shandong University
Priority date: 2022-01-07
Filing date: 2022-01-07
Publication date: 2022-04-15
Anticipated expiration: 2042-01-07
Also published as: CN114361393B

Abstract

The invention belongs to the technical field of materials, and particularly relates to a method for simply preparing a self-supporting silicon cathode and application of the method in a lithium/sodium battery. The method comprises the following steps: depositing metal lithium on a current collector, then placing the current collector in a silicon tetrachloride/silicon tetrabromide solution to obtain a silicon material on the surface of the current collector, and drying to obtain the self-supporting silicon cathode. The silicon-based material is obtained by the in-situ reduction method, the obtained material is uniform and has a self-supporting structure, the use of a conductive agent and a binding agent can be avoided, the working procedures are reduced, the cost is reduced, and the energy density of the battery is improved. By adjusting the deposition amount of the metallic lithium, the amount of silicon can be controlled. By adjusting the time of the displacement, the relative amounts of lithium and silicon in the product can be adjusted, thereby controlling the conductivity thereof.

Description

Method for simply preparing self-supporting silicon cathode and application of self-supporting silicon cathode in lithium/sodium battery

Technical Field

The invention belongs to the technical field of energy storage, and particularly relates to a method for simply preparing a self-supporting silicon cathode and application thereof.

Background

The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.

The silicon cathode has the advantages of high theoretical specific capacity of lithium storage, low working voltage, rich energy storage, no toxicity and the like. However, several problems have limited its further commercial development. (1) The preparation process is complex, the required equipment is complex, the yield is low and the cost is high. (2) The large volume expansion is generated in the circulation process, the structure of the material is damaged, and the electrode material is pulverized and falls off, so the circulation performance is poor. (3) Silicon has poor conductivity and thus poor rate capability.

The inventor finds that: the defects of complex preparation, high cost, poor conductivity and the like in the prior art are important for developing a simple method for preparing the silicon cathode.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a method for simply preparing a self-supporting silicon cathode.

In order to achieve the technical purpose, the invention adopts the following technical scheme:

in a first aspect of the invention, a method for simply preparing a self-supporting silicon cathode is provided, which comprises the following steps:

depositing metal lithium on a current collector, then placing the current collector in a silicon tetrachloride or silicon tetrabromide solution for a displacement reaction to obtain a silicon material on the surface of the current collector;

and drying the silicon material to obtain the silicon material.

In a second aspect of the invention, there is provided a self-supporting silicon electrode prepared by the above method.

In a third aspect of the invention, a lithium ion battery is provided, and the negative electrode is the self-supporting silicon electrode.

In a fourth aspect of the invention, a sodium ion battery is provided, and the negative electrode is the self-supporting silicon electrode.

The invention has the beneficial effects that:

(1) the silicon-based material is obtained by the in-situ reduction method, the obtained material is uniform and has a self-supporting structure, the use of a conductive agent and a binding agent can be avoided, the working procedures are reduced, the cost is reduced, and the energy density of the battery is improved.

(2) By adjusting the deposition amount of the metallic lithium, the amount of silicon can be controlled.

(3) By adjusting the time of the displacement, the relative amounts of lithium and silicon in the product can be adjusted, thereby controlling the conductivity thereof.

(4) The operation method is simple, low in cost, universal and easy for large-scale production.

(5) The research finds that: compared with silicon materials prepared by an in-situ growth method, an electrodeposition method, a template method and an etching method, the silicon material prepared by the method disclosed by the invention through the replacement of the metal lithium not only keeps better electrochemical performance, but also is more uniform in silicon particles in the obtained product. In addition, the bonding force between the silicon and the current collector is stronger.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

Fig. 1 is an XRD pattern of the silicon material prepared in example 1.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

As described in the background, the present invention addresses the deficiencies in the prior art by providing a highly conductive carbon material.

The method comprises the following steps:

depositing metal lithium on a current collector, then placing the current collector in a silicon tetrachloride/silicon tetrabromide solution to obtain a silicon material on the surface of the current collector, and drying to obtain the self-supporting silicon cathode.

The lithium metal is deposited by electrodeposition or fusion deposition.

The current collector is copper, aluminum, carbon cloth, MXene and the like.

In a third aspect of the invention, there is provided a use of the above silicon electrode in a lithium ion battery.

In a fourth aspect of the invention, there is provided a use of the above silicon electrode in a sodium ion battery.

The present invention is described in further detail below with reference to specific examples, which are intended to be illustrative of the invention and not limiting.

In the following examples, the copper-based current collector is 200X 0.012mm 1 Kg/roll of bifocal copper foil.

Example 1

A self-supporting silicon material:

deposition of metallic lithium:

assembling a half cell, using copper foil as a working electrode, using a lithium sheet as a counter electrode and a reference electrode, using an electrolyte of 1M LiPF6+ EC/DEC, and having a deposition parameter of 1mA cm^-1The time is 2 h.

And (3) replacement reaction: and (3) putting the obtained copper-based current collector into silicon tetrachloride, soaking for 30min, taking out, and drying to prepare the self-supporting silicon electrode, wherein an XRD (X-ray diffraction) pattern of the self-supporting silicon electrode is shown in figure 1.

And (3) performance testing: the silicon is used as a working electrode, the lithium sheet is used as a counter electrode and a reference electrode, and the electrolyte adopts 1M LiPF₆+ EC/DEC/10% FEC, current density 500mA g^-1Voltage interval of 0.01V^-3V, the capacity retention rate of the battery with the composition after 100 weeks of cycle is 86.8%, and the good performance of the silicon electrode is proved.

Example 2

A self-supporting silicon material:

deposition of metallic lithium:

assembling a half cell, using copper foil as a working electrode, using a lithium sheet as a counter electrode and a reference electrode, using an electrolyte of 1M LiPF6+ EC/DEC, and having a deposition parameter of 2mA cm^-1The time is 0.5 h.

And (3) replacement reaction: and (3) putting the obtained copper-based current collector into a silicon tetrachloride solution, soaking for 35min, taking out, and drying to prepare the self-supporting silicon electrode.

Example 3

A self-supporting silicon material:

deposition of metallic lithium:

assembling a half cell, copper foil as a working electrode, lithium sheet as a counter electrode and a reference electrode, electrolyte of 1M LiPF6+ EC/DEC, deposition parameter of 10mA cm^-1The time is 0.02 h.

And (3) replacement reaction: and (3) putting the obtained copper-based current collector into a silicon tetrachloride solution, soaking for 20min, taking out, and drying to prepare the self-supporting silicon electrode.

Example 4

A self-supporting silicon material:

deposition of metallic lithium:

assembling a half cell, copper foil as a working electrode, lithium sheet as a counter electrode and a reference electrode, electrolyte of 1M LiPF6+ EC/DEC, deposition parameter of 5mA cm^-1The time is 0.2 h.

And (3) replacement reaction: and (3) putting the obtained copper-based current collector into a silicon tetrachloride solution, soaking for 15min, taking out, and drying to prepare the self-supporting silicon electrode.

It should be noted that the above-mentioned embodiments are only preferred embodiments of the present invention, and the present invention is not limited thereto, and although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications and equivalents can be made in the technical solutions described in the foregoing embodiments, or equivalents thereof. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for simply preparing a self-supporting silicon cathode is characterized by comprising the following steps:

and drying the silicon material to obtain the silicon material.

2. The method for preparing a self-supporting silicon anode in a simplified manner as claimed in claim 1, wherein the current collector is copper, aluminum, carbon cloth or MXene.

3. The method for preparing the self-supporting silicon negative electrode in a simple manner according to claim 1, wherein the soaking time of the current collector deposited with the metallic lithium in the silicon tetrachloride/silicon tetrabromide solution is 15-35 min.

4. The method for simply preparing a self-supporting silicon anode of claim 1 wherein the deposition is electrodeposition or fused deposition.

5. The method for preparing a self-supporting silicon negative electrode according to claim 4, wherein the electrodeposition uses copper foil as a working electrode and lithium sheets as a counter electrode and a reference electrode.

6. The method for preparing a self-supporting silicon anode in a simplified manner as set forth in claim 4, wherein the electrolyte is LiPF6+ EC/DEC.

7. The method for simply preparing the self-supporting silicon cathode according to claim 4, wherein the deposition parameter is 1-10 mA cm^-1The time is 0.2-2 h.

8. A self-supporting silicon electrode made by the process of any of claims 1-7.

9. A lithium ion battery wherein the negative electrode is the self-supporting silicon electrode of claim 8.

10. A sodium ion battery wherein the negative electrode is the self-supporting silicon electrode of claim 8.